


Fuck Me in the Ass 'cause I love Sothis

by LaceKyoko1138



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Anal Fingering, Anal Sex, Creampie, Cunnilingus, F/M, Friends With Benefits, Making Out, Pre-Timeskip | Academy Phase (Fire Emblem: Three Houses), Religious Conflict, Slight Misogyny, it's sylvain so what do you expect lmao, mercie schools him don't worry
Language: English
Status: Completed
Published: 2020-06-25
Updated: 2020-06-25
Packaged: 2021-03-04 02:27:22
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,027
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24906061
Author URL: https://archiveofourown.org/users/LaceKyoko1138/pseuds/LaceKyoko1138
Summary: Mercedes has inner conflict with her desires and her religion. She comes up with an idea where she can get what she want, but still be pure in the eyes of the goddess. Sylvain is there to help.Based offFuck Me in the Ass 'cause I love Jesusby Garfunkel and Oates.
Relationships: Sylvain Jose Gautier/Mercedes von Martritz
Comments: 1
Kudos: 33





	Fuck Me in the Ass 'cause I love Sothis

**Author's Note:**

> It's been some time, hasn't it? The world has me stressed but I'm getting back into the swing of things.
> 
> This is really a silly fic in some ways. Please don't take any of this seriously. I hope you enjoy regardless!

Mercedes was at her core a good girl. Church abiding. Helpful. Kind. She never said a bad word about anybody and she didn’t do things deemed bad, at least, not openly. However Mercedes did have an odd fascination with ‘bad’ things and sometimes couldn’t help herself.

She sometimes dabbled in making what was soon known as ‘edibles,’ simply put, baked goods with traces of marijuana in them. She made different dosages and typically her clientele enjoyed the higher ones, particularly if they were more experienced with them.

Mercedes was studying Reason magic under the professor. At first she had wanted to learn the bow and focus on Faith magic, something she had an innate ability for, but the professor had reasoned with how high her magic stats seemed to be, she’d make a far better magic-based unit, whatever that meant. But Mercedes dutifully listened and found she rather enjoyed the spells. Setting something ablaze on her own command was...invigorating.

Not that she’d tell anyone that.

Something else she wouldn’t tell anyone was that she sometimes sneaked out with Sylvain and they would make out in the green house. No one was typically in there after hours so it was perfectly private for Garreg Mach Monastery’s favorite philanderer and the resident student nun.

At first it was harmless. Sylvain hit on her as he hit on all women and Mercedes playfully allowed him. Sometimes she teased back. But it was with that further teasing that coaxed Sylvain into actually pursuing her. It was a bit awkward for her at first, since there hadn’t really been a man interested in her since she was younger and it wasn’t a very fond memory, but she let him take her to tea once and finally decided that she could never love Sylvain. She would never want to marry him. He was actually quite smart and very neat, but the underlying darkness she knew he held was not something she would want to be involved with.

So naturally, they became fellow students who sometimes touched each other in shadowy places. No one needed to know that.

In this current moment, Mercedes was at Sylvain’s mercy, writhing under him as their tongues slid together, moaning into each other’s mouths. Her back was against one of the pillars in the green house and Sylvain had effectively pinned her there with his long arms. His leg was between her thighs, rubbing sensually against her. Her arms were wrapped around his neck as he craned down to lock lips with her.

There was always that ache though. Mercedes sometimes wanted to go further. She craved it. She rarely touched herself, and she could never let a man have sex with her out of wedlock, because while the teachings of Seiros didn’t explicitly say anything about premarital sex, many of its followers did have things to say, so Mercedes felt that as a true woman of Sothis, she shouldn’t. Yet Sylvain awakened in her a dark desire to just _fuck_.

She could tell he was into it too. The hard lump pressed into her left thigh told her everything she needed to know. Their kissing was exceeding past its normal limit and she knew that the time was now apparently. Sylvain wanted her and she wanted him in return.

Of course, she shouldn’t let him. What if he released inside and she got pregnant? Mercedes was one of the older students and helped in the infirmary sometimes so she was very aware of where babies came from. She actually had to give her Annie...the talk. Really.

But, Mercedes was a lover of dark things. She knew there were ways she could let Sylvain inside and still enjoy herself.

As Sylvain got more and more handsy, Mercedes did as well. He was taking off her shawl, unbuttoning her shirt. She let him, because she was doing the same to him.

Shirts were put aside. Mercedes was just in her brassiere. Sylvain was quickly taking his pants off. She felt self-conscious at first; this was the first time a man had seen her so exposed in...well, she wouldn’t think of that. Sylvain was shimmying her skirt off. It fell along with her panties. She tried covering herself at first but when Sylvain’s hand grabbed at her ass, she had an idea.

She pulled away and unclasped her bra. Sylvain smiled at seeing her breasts in full.

“Damn, Mercie. Can’t wait to pop one in my mouth.”

She thought it was a bit uncouth, even clumsy, but she giggled and let him. As he sucked and licked at her breasts, the tingly sensation of arousal kept pulling at her. She felt her legs squirm, thighs clamping together because she didn’t want to seem so wanton, but goddess she wanted to spread her legs and have him place his mouth there instead.

Sylvain was working his way down, and when he got to the prize, he gently spread her thighs. He looked up at her, eyes peering through his bangs. She nodded and he let himself have at her.

His tongue glided across her sex, tickling her clit and delving inside her. Mercedes gasped and cried out. It had felt better than she thought it would but she needed more.

Sylvain was working his magic, sucking on her, kissing her thighs, causing her to make keening squeaks louder and louder until she was moaning so loud, he had to stop. He stood up and held his hand over her mouth.

“Mercedes, we’ve got to keep somewhat quiet. The knights might hear.”

She pulled his hand away from her mouth. “I-I’m sorry, but it just felt so good...”

“Heh, that’s what I like to hear. I’m not mad, but we do need to be careful.”

“Of course.”

He got back on his knees, this time fingering her as well and Mercedes felt a buildup of pleasure. Within seconds, he had her coming.

“A-ah...” she barely made out. She had to keep quiet, she had to keep quiet… Her muscles were shaking, her thighs clamping around his face, and she found her hands in his hair, coaxing him to continue. She rode out her orgasm and Sylvain let up, standing up.

“So, uh, do you want to return the favor?”

Oh how she did. It was a bit daunting at first, considering she had never done _that_ before, but it was all instinct as she sunk to her knees and got to work. She was gentle at first, bobbing her head shallowly, but Sylvain’s long fingers were in her hair before long, pushing her to go a bit deeper than before.

Mercedes doubted she could fit all of him in her mouth, but she wanted to try and push it. Inch by inch she took him, but when he hit just past the back of her tongue she found herself gagging. She tried to relax, but she couldn’t get him past that point.

She pulled herself away, disappointed that she couldn’t deepthroat him the way he wanted, but then she remembered how he grabbed her ass, how she wanted him inside, but couldn’t because that was unholy.

“Sylvain, I have an idea.”

Sylvain looked down to see sweet, innocent Mercedes on her knees, looking coyly up at him, cock brushing her chin. “Yeah?”

“You want to come, right?”

Goddess he wanted to. He was so close and she stopped. “Y-yeah?”

“You want...to be inside me, right?”

“Yeah…?”

“Good!” She got up and turned around, bending forward, but instead of spreading her thighs so he could ease into her pussy, she spread her ass cheeks. “I’m sure you’ve done this before?”

Sylvain had _never_ fucked a _girl_ in the ass before. He was still denying that one time he stayed over at the Fraldarius’ estate and he and Felix got into the fancy cognac and wine...trading stories of first crushes, which was hilarious because Felix was emotionally constipated. They were young and drunk and never spoke about it again, but they were still friends.

But Sylvain _had_ done anal before, and he knew that just plowing into Mercedes inside the green house with no lube while she was just bending over the flowers was not the way to do it.

“Hey, if you want to do that, we’ll need to go back to my room.”

“O-oh? But won’t Ingrid…?”

“Hey! Yeah she tries to dissuade me, but it’s pretty late, she’s probably asleep, and as long as we’re quiet, she’ll never know.”

“Oh. Okay.” So they quickly dressed and quietly made their way back to the dorms.

Sylvain hated how the floorboards seemed to creak as they walked to his room, but Mercedes had managed to avoid all the squeaky boards so it only sounded like Sylvain was walking down the corridor. Ingrid would be none the wiser.

Sylvain ushered Mercedes in and he locked the door behind him. He looked at her and she nodded. They started ripping their clothes off before the arousal went away and it would be too awkward to try this again.

Sylvain pushed Mercedes face first onto the bed. She was on all fours, and looked at him as he tried to quietly dig through some things in the chest at the foot of his bed.

He procured a small bottle of some oil and uncorked the bottle, pouring a little on his fingers, and he warmed it between his hands.

“Mercedes,” he whispered. “I want you to know that this will be a bit painful at first. And you’re not a guy so you probably won’t enjoy it like a man would.”

Mercedes knew some things about male anatomy just from studying healing with Manuela. “Ah, I think I understand what you mean.” Something about a prostate. Whatever.

“You still want to go through with this?” he said as he wormed a finger into her asshole, as if to warn her of what was to come.

Strangely enough, Mercedes _liked_ it. It was foreign, it was wrong, but if it meant she would be ‘unsullied’ in the eyes of the followers of Seiros, who cared?

“Y-yes...” she breathed out. “Please. I-I like it, Sylvain.”

He quirked an eyebrow as he continued working her ass. “You do?”

“Yes. It feels a bit weird, but it’s a good weird.”

“Okay then.” He wormed another finger inside her.

This time it hurt. She felt her hole painfully stretch as his long and bony fingers penetrated her. But Sylvain was as gentle as the act would allow, and he twisted and bent his fingers in a way that would only benefit Mercedes later.

It felt like a millennium before he finally put in a third finger. This was the tightest fit yet, but if he had gotten this far, she’d be ready soon. He added a little more lubricant to his fingers and continued to stretch her.

Mercedes would squeak if he turned there, or moan if he bent here, and Sylvain liked that he could get a woman off just by playing with her butt. It was unusual, but if this worked out, he could probably have a lot of fun with her without worrying about finding those special herbs to discourage pregnancy in case he screwed up and didn’t pull out in time. She liked his oral skills, so he knew he could at least get her off.

If anything, fucking Mercedes would be a good thing for him. He knew from the get go she didn’t want anything more, a rarity for him. This meant he could go buck wild and not have to worry about hurting her feelings later if he ended up getting arranged into a marriage. He could actually _fuck_ her without abandon; he could come inside because this wasn’t her pussy! He was about to pound into that deliciously round ass. And it seemed she liked anal play, so really, this was turning into a beautiful arrangement.

“Okay, Mercie, I think you’re ready,” Sylvain finally whispered. He pulled his fingers out and began coating his dick with oil.

“Oh Sylvain, I feel so empty without you inside,” she said in that breathy way of hers.

Was...was she trying to dirty talk with him? Oh this was getting even better.

“Don’t worry babe, you’re about to get a whole lot of me.” He aimed the tip at her hole. “I’m going in.” He gently pushed forward, holding onto her hip with one hand as he held himself steady with the other. She gasped a bit but Sylvain had expertly stretched her so it wasn’t completely unpleasant. He kept pushing in until he knew he had fully sheathed himself inside her.

“See Mercie? That wasn’t so bad.”

She caught her breath. “Yeah. It only stings a little.”

“Hey, let me know if you need me to stop. I don’t want to actually hurt you.”

In response to that, she pushed her ass against him. “Quit talking and fuck my ass.”

He almost choked on his own spit at hearing the expletive come out of her mouth, but it only turned him on more, so he did as she said.

He started a slow pace but Mercedes urged him to go faster. He did, sliding in and out of her ass, really diving deep on the push and pulling out viciously. His pace soon became brutal and it was in this moment, in this total, utter moment of depravity that Mercedes thought she could totally live like this. Like a harlot at a tavern, bedding a man that was treating her like a fuck toy, but it was okay because she liked it, as if this was her purpose in life, to be fucked silly by Sylvain Jose Gautier. Goddess, she might love him after this!

A silly thought though, because she knew once it was done, she’d be a fool to fall for someone who literally only saw her as a way to get off. But she saw him that way too, so maybe that was for the best.

Sylvain kept pounding away, but he was finding his limit. “M-Mercedes...” he wheezed.

“You can come, Sylvain. Please, come inside me!” She felt like she could too, she was so close but her orgasm was still out of reach.

He made some sort of gurgled grunt that Mercedes found strangely hot and then he stilled. She felt his dick twitch inside her and then she was being pumped full of cum. Oh goddess it was a lot.

Sylvain pulled out and promptly collapsed next to her. Mercedes felt like if she moved it would all come rushing out of her. But it was sliding out of her regardless so she needed to move before it started dripping onto her pussy.

She sat back on her haunches and it oozed out. She made a face. “Do you have a handkerchief?”

“Ah, why-OH SHIT YES.” Sylvain quickly leapt out of bed and found one in the chest and threw it at her. Mercedes tried to get most of it out of her and onto the handkerchief and wipe up what had already come out, but she knew Sylvain’s sheets would need to be laundered.

“Sorry, Mercie, I forgot what a mess this could be...”

“It’s fine. I liked it.” Feeling semen rush inside and just as quickly slide out was surprisingly exhilarating. “And at least we know you didn’t knock me up!”

Sylvain thought Mercedes’ sense of humor was a bit off, but he chuckled anyway. “Yeah, true.” He then looked at her. “You didn’t…?”

“Hm? Oh!” She looked away. “I didn’t, no.”

“I’ll take care of you.” Sylvain pushed her back down, this time her legs dangling off the bed. He found his way between them and began working her with his tongue.

Mercedes finally reached her limit and came, gasping his name. She finally looked down to see his face covered in her essence, but his lopsided smirk told her he was happy.

“Hey, Mercie, I-”

There was a knocking on his door. “Sylvain! Go to bed!”

Ah, yes, dutiful Ingrid, always spoiling his fun.

Mercedes quickly dressed. Sylvain frowned for a second, knowing that she wouldn’t want to stay and cuddle in post-coital bliss, but neither did he. Did he? Did he not? He wasn’t sure. Sex with Mercedes left him very befuddled, despite the post-orgasmic clarity.

Mercedes, not knowing how to say goodbye, bowed slightly, but Sylvain straightened her.

“You...you can stay, you know?”

“Oh, but wouldn’t that upset Ingrid?”

“She already knows someone is in here with me. You might as well stay.”

“But, Sylvain, you don’t...you don’t actually like women.”

He sputtered. “Mercedes, I literally just fucked you.”

“No, not that. You can have sex without love. Trust me, I know.” She smiled sweetly at him. “But I know that you think women only want you for your status or your crest. You think you’re a studhorse.”

“How did you…?”

“Professor Byleth is surprisingly talkative at tea time. I find out all sorts of fun things. Plus, you’re easy to read.”

Oh.

“What I mean is...you don’t think very highly of us. I understand why you feel that way, but please understand that there are women in your life who do like you for you. I like you. I think you’re fun.”

He looked away sheepishly, more exposed than he already was. “I...Thanks, Mercedes. That actually means a lot.”

He was just standing there, stark naked, and she was fully dressed, ready to leave.

“I...If you want to stay, then please, stay. But if you’d rather leave...”

“I should go, Sylvain. We both know that what this was, wasn’t _that_.”

That? Did she mean love? Sylvain wondered. They may have both transferred to Professor Byleth’s class, but Sylvain still somehow found Mercedes to be an enigma.

He thought he was being so cool. She read right through him. He realized he knew less of himself than he thought.

Mercedes left, because while she may have only liked Sylvain, she loved the goddess more. And the goddess would want her to respect herself.


End file.
